Highly concentrated surfactant formulations in liquid form have the recognized advantages of reduced product bulk for manufacture and distribution, while permitting the user to readily add water thereto for preparing the proper dilution for use. Such concentrates containing up to 100% active ingredients have been prepared (See, for example, U.S. Pat. Nos. 3,549,544 and 3,709,838). While such prior art formulations have provided satisfactory cleaning power for some applications, they have not been very effective for heavy duty type cleaning uses, unless the user on dilution of the concentrate adds ammonia or other aqueous alkali. Prior to the present invention, pre-formed surfactant liquid concentrates containing concentrated alkali have apparently been limited to preparations in the form of pastes. (See, for example, U.S. Pat. No. 3,583,923).
The addition of concentrated aqueous alkali to concentrated liquid surfactants tends to make the formulations unstable, causing hazing and the formation of precipitated material. Consequently, where the amount of water in the concentrate is to be limited to maximize the content of active ingredients, it has been difficult to incorporate sufficient alkali for effective action of the alkali on dilution of the concentrate. For use as a heavy duty cleaner where the concentrate contains 90% or more active surfactant ingredients, use dilutions as great as 1:300 to 1:400may be desirable. It will therefore be seen that unless the aqueous alkali is present in a concentration permitting a corresponding dilution while remaining effective, there will be a need to add additional alkali on use and the desire to perform a total concentrate of alkali and liquid surfactants is defeated. It is believed that the present invention for the first time provides a satisfactory solution to this problem.